2007. december 1., szombat

Another halogen lamp display from Rovaniemi

A bright halogen spotlight and diamond dust is a magic combination.

Spot yourself exactly in the middle of the beam and breathtaking halo views may rewards you. An outsider will see just somebody bathing in the light and may wonder what is going on. There might be a Moon in the sky at the same time - like in the case shown here - but it shows hardly no halos at all. The lamp creates its own universe of halos.

The Ounasvaara snow guns created this display last night in Rovaniemi in the beam of a Cyclops Thor Platinum X-15 halogen lamp. Because of the lack of 46° lateral arcs, this display must have been dominated by Parry crystals. Indeed, in the lower right image there are both upper and lower Tape arcs as an indication of Parry orientation.

An interesting feature is seen in the images on left (the lower image is an unsharp masked from the upper). There seems to be a loop inside the helic arc. Much like the loop formed by the subanthelic arc.

On the upper right is a simulation that shows a quite similar loop (arrow). The crystals in simulation are Parry oriented and they are semitriangular, a half way between a triangle and regular hexagon. The thing in the photo looks to me like a halo and it might be the one shown in the simulation. I have not raytraced it, so I don't know what it might be called. There are some differences in the loop sizes between the simulation and the photos, but then again the projections are not exatly the same.

A bit more could be said about the results of the last night, but this must do for now. The simulation was made with a program by Jukka Ruoskanen.

3 megjegyzés:

  1. I was thinking that Jarmo is going wrong with his displaced Hastings, but indeed, that's how it seems to be. Spectacular insight!

    So the term 'rotated' here has a different meaning than 'displaced' then?

  2. very nice displey.Congratulations marko!

  3. Wow Marko congrads in dicovering a new halo form!!! This is just amazing what you are seeing from divergent light sources. One thing I have been wanting to tell you I think would be cool is to take a hi-power light and mount it on a pulley system on a very tall pole and have wireless remote and with the touch of a button move the light up or down and watch the halos change their shape with elevation. This will allow one to make halos into an art so long there are diamond dust choking the sky.

    Again congrads on you photos Marko.